During the construction of a multi-storey car park, the Hamburg City Cleaning Department installed an environmentally friendly base layer with the alternative building material emvau-schlacke below the roadway on the ground floor. The required load-bearing capacity for the areas exposed to heavy traffic was at least 150 MN per square metre. This is why emvau-schlacke was particularly suitable, as it can even achieve values of 200 MN per square metre. The use of emvau-schlacke is up to 40% cheaper than conventional building materials.